Russia described recent events in Kazakhstan as a "foreign-inspired" attempt to undermine security, adding Moscow will consult Kazakhs and other allies on possible further steps to support a "counter-terrorist operation" and to unblock critical infrastructure.

The Russian Foreign Ministry said Thursday in a statement: "We regard the recent events in a friendly country as an attempt, inspired from the outside, to undermine the security and integrity of the state by force, using trained and organized armed formations."

Ethnic Russians, mostly Orthodox Christians, make up nearly a quarter of Kazakhstan's population. The two countries have significant economic and cultural ties.

Russia has already sent paratroops to Kazakhstan as part of a peacekeeping force after the energy-rich Central Asian country was hit by the biggest wave of unrest there since the 1991 collapse of the Soviet Union over rising fuel prices.

Under increasing pressure, President Kassym-Jomart Tokayev appealed overnight to the Russia-dominated Collective Security Treaty Organisation (CSTO), which includes five other ex-Soviet states, to combat what he called "terrorist groups" that had "received extensive training abroad."

Within hours the alliance said the first troops had been sent, including Russian paratroopers and military units from the other CSTO members, in its first major joint action since its founding in 1999.

"Peacekeeping forces ... were sent to the Republic of Kazakhstan for a limited time to stabilize and normalize the situation," the CSTO said in a statement, without specifying the number of troops involved.

The CSTO's current chairperson, Armenian Prime Minister Nikol Pashinian, earlier announced the alliance would agree to the request, saying Kazakhstan was facing "outside interference."

Footage released by the Russian Defense Ministry showed military transport planes being loaded with troops and armored trucks before taking off from a snowy runway for Kazakhstan.

In the worst reported violence so far, police said dozens of people were killed in overnight battles with security forces at government buildings in the country's largest city Almaty.

"Extremist forces tried to assault administrative buildings, the Almaty city police department, as well as local police commissariats. Dozens of assailants were eliminated," police spokesperson Saltanat Azirbek was quoted as saying by Russian news agencies.

Tokayev said in a televised address early Thursday that "terrorists" were seizing buildings, infrastructure and small arms, and battling security forces.

Military forces had deployed en masse in the streets of Almaty and were firing live rounds, according to footage shown Thursday on Russian television.

Videos on social media showed pillaged shops and burned buildings in Almaty, automatic gunfire in the streets and residents screaming in fear.

Officials said more than 1,000 people had been wounded in the unrest, with nearly 400 hospitalized and 62 in intensive care.

As of midday Thursday, more than 350 security officers had been wounded and 13 killed, including two who had their heads cut off, officials told local media.

There were reports of looters attacking and ransacking the offices of local television channels and surrounding two hospitals in Almaty.

Protests spread across the nation of 19 million this week in outrage over an increase in prices for liquid petroleum gas (LPG), which is widely used to fuel cars in the west of the country.

Thousands took to the streets in Almaty and in the western province of Mangystau, saying the price rise was unfair given oil and gas exporter Kazakhstan's vast energy reserves.

Protesters were reported to have stormed several government buildings on Wednesday, including the Almaty mayor's office and the presidential residence.

The full picture of the chaos was unclear, with widespread disruptions to communications including mobile phone signals, the blocking of online messengers and hourslong internet shutdowns.

The protests are the biggest threat so far to the regime established by Kazakhstan's founding president Nursultan Nazarbayev, who stepped down in 2019 and hand-picked Tokayev as his successor.

Tokayev tried to head off further unrest by announcing the resignation of the Cabinet early on Wednesday, but protests continued.

Tokayev also announced he was taking over from Nazarbayev as head of the powerful security council, a surprise move given the ex-president's continued influence.

With protests escalating, the government late on Wednesday said a state of emergency declared in protest-hit areas would be extended nationwide and in effect until Jan. 19. It imposes an overnight curfew, restricts movements and bans mass gatherings.